IS 13416-4: Recommendations for preventive measures against hazards at workplaces, Part 4: Timber structures

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IS 13416-4 (1994) : Recommendations for preventive measures
against hazards at workplaces. Part 4: Timber structures
[CED 29: Construction Management including safety in
Construction]

Jawaharlal Nehru
'Step Out From the Old to the New"

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PROTECTED BY COPYRIGHT

IS 13416 (Part4): 1994
( Reaffirmed 2003 )

Indian Standard

PREVENTIVE MEASURES AGAINST

HAZARDS AT WORKPLACES —

RECOMMENDATIONS

PART 4 TIMBER STRUCTURES

UDC 699.81:658.382.3

© BIS 1994

BUREAU OF INDIAN STANDARDS

MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG
NEW DELHI 110(X)2

July 1994 Price Group 2

Safety in Construction Sectional Committee, CED 45

FOREWORD

This Indian Standard (Part 4) was adopted by the Bureau of Indian Standards, after the draft finalized by
the Safety in Construction Sectional Committee had been approved by the Civil Engineering Division
Council.

Components of timber structures commonly used in building construction are columns, beams, trusses,
rafters, purlins, etc of different sizes and forms. Construction and erection of timber structures, though
appear to be simple, involve considerable hazards. Depending on their weight and mode of fixing
particularly in space or height, some precautionary measures should be adopted during works for
necessary safety of the works and the workers.

There are various methods in vogue in industries in India and abroad to prevent accident while working
on timber structures. This standard has been formulated for providing general guidance in respect of
safety requirements to all those involved in limber works, such as the designers, engineers, architects,
contractors, supervisors, carpenters and all other workers. This standard also covers the merits and
demerits of the institutional practice and suggests suitable remedial measures. However, the list is not
exhaustive and any other methods considered to be good depending on the facilities of works may also be
adopted, if approved by the competent authority. In addition, from fire safety point of view, a reference
may be made to IS 13416 (Part 5) : 1994 ^Recommendations for preventive measures against hazards at
workplaces : Part 5 Fire safety'.

The composition of the technical committee responsible for the formulation of this standard is given in
Annex B.

IS 13416 (Part 4 ) : 1994

Indian Standard

PREVENTIVE MEASURES AGAINST

HAZARDS AT WORKPLACES —

RECOMMENDATIONS

PART 4 TIMBER STRUCTURE

1 SCOPE

1.1 This standard (Part 4) lays down the safely
requirements for the works and workers, while
working on timber structures starting from process-
ing the timber, jointing them to make beams,
columns, trusses, purlins, etc and erecting them to
make the structures including structures with roof
covering.

1.2 This standard does not cover the safety require-
ments during masonry or concrete works for floor-
ing, walling, etc of the structures.

2 REFERENCES

The Indian Standards listed in Annex A are neces-
sary adjuncts to this standard*

3 SAFETY IN TIMBER HANDLING

3.1 On Ground

Timber pieces, big or small, may cause injury if
carelessly handled during processing, fabrication,
erection and transportation. A slender piece with
sufficient length should not be attempted to
process, push or pull so that it may not get broken
at weaker points like at knots with a sudden thrust
on the persons working on it. Smaller pieces
should be carried in bundles. Carts, trolleys, trucks,
etc should be used as per convenience, for heavier and
bigger pieces. For proper handling of the timber by
the workers, stronger ropes, wirts, aiding poles or
rods, etc should be used. While using trucks for
transportation, sufficient care should be taken in
kiading and unloading the bundles and bigger pieces
particularly over the sloped surfaces so that these do
not amse any injury to the people working bclowwho
should be given clear sound or signal to leave the
place well in advance.

3.2 In Space

In cases of works in space or height where the pieces
are required to be taken for fixing with adjacent
members, these should be lifted by using wires or
ropes, cranes, etc while nobody should be allowed
^10 stand or work under the structure.

3.2.1 No fragile material should be used as ladder
or supporting aid of the workers during works in
space.

4 S.AFETV IN TOOL HANDLING

4.1 In timber works, right from the stage of
processing of timber pieces, different types of tools
such as saws and drills of various sizes, hanmiers,
planers, chisels, etc are used. The tools should be
carefully checked for sharpness before starting the
work. Particular attention should be paid to tools with
wooden handles or butts. In no case tools like hammer,
chisel, handsaw, screw-drivers, etc should be used with
loose handles as it may cause injury by falling suddenly
on the people working nearby. Blunt tools and tools
with broken or loose handles are certain to retard the
progress of work in addition to causing constant in-
convenience to the concerned carpenters.

4.2 During work in height, tools like drills, chisels,
hammers or even the box containing them or any
other containers or nails and bolts should not be
kept haphazardly. This may inadvertently harm the
people working there or below by being dislodged
due to movement of carpenters. In general, no tool
or the box carrying tools, etc should be left within
500 mm of the edge of a high working platform.

5 SAFETY IN WORKING IN HEIGHT

5.1 Wearing ofSafety Dress Material

Proper dress including shoes, gown or apron, head
gear, etc should be used by the carpenters, which
are essential safety measures in carpentry works,
and safety belts should be used while working in
space or height.

5.1.1 Wearing of Head-Gear

All the workers should wear suitable head gear/liel-
met (IS 2925 : 1984) for precaution against any
untoward happening.

5. 1 .2 Wearing of Shoes

Workers should wear such type of shoes that will
ensure freedom of movement as well as minimize
chances of fall from height or roof.

!S: 13416 (P3rt4):lW4

5.2 Spreading of Nylon Rope Nets or Galvanized
Wire Mesh

In roofing work, nylon rope net or galvanized iron
mesh should be spread^ duly fixed to the framework
below the roof, covering the area from ridge purlin
to eave purlin.

5.3 For executing works on the overhanging por-
tion of pitched roof, it is better and easier to work
on pitched roof, by spreading a strong bamboo-
culm or 70 mm to 1 00 mm diameter eucalyptus pole
along the lower side parallel to eave duly bound by
strong ropes from the ridge. The workers will be
able to work by making the bamboo or eucalyptus
pole as supporting base. The system of such loose
support over pitched roof will not cause hinderance
in placing the roof covering.

6 SAFETY IN FABRICATION OF STRUC-
TURAL COMPONENTS

6.1 Fabrication of Beams^ Trusses, etc

The joints in beam_s, trusses, etc are fixed earlier in
fully fabricated structures but in case of semi-prefab
structures, the positions for jointing with necessary
prebores and finished ends are duly marked for easy
identification and fastening with adjacent parts by
using nails or bolts. Simple type of joints like butt
fish joints should be employed in joining truss
members placed over the layout (full scale) made
on workshop floor.

6.1.1 Though it is desirable to use defect-free tim-
ber, the same is not always available. Defects, like
knots, cross grains, checks, shakes, etc should
be accommodated on the timber as per the codal
provisions given in IS 3364 (Part 1) : 1976 and
IS 3364 (Part 2) : 1976. Timber pieces with the
accommodable knots particularly at central zone of
beams, purlins, etc should be so placed as to bring
the knotty face in the compression zone for ade-
quate safety.

6.1»2 Use of Fasteners

Fasteners, like mild steel nails and bolts should be
used in prebored holes to avoid splitting of the
members during driving. The bore diameters for
nails should be a bit less, say about 0.8 times the
diameter of the respective nails and a bit more for
the bolts with edge, end, intermediate and row
distances as per the provision given in IS 2366 : 1983
and IS 11096 : 1984 respectively lor nail and bolt
joints. Operation of electric drills for long period
or time on harder and thicker pieces, and forcible
or casual drivingofnails on hardci timbers without
preboring should be avoided. Otherwise such nails,
iduring hammering, may suddenly and swiftly get
thrown out causing serious injurv' to the carpcnicr
himselfor any other person helping h::, i v ling

nearby. Protruded ends of mild steel nails should
either be clenched or cut off at the concerned face
of the timber. Unnecessarily extended length of
bolts beyond the nuts should also be cut and filed.
All these, if inadvertently left out, may cause
serious injuries to workers at any stage of fabrica-
tion, erection or application of paints, creosote, etc.

6.2 Fabrication and Fixing of Columns

Proper fixing of the timber columns, pariiculariy
box types or spaced columns fabricated by use of
assorted planks and spacer blocks generally require
at the base ready made dwarf RCC footing having
extended iron straps duly prebored. This is an
essential arrangement for safe erection of the struc-
ture. The columns should have suitable bearing at
the top to accommodate the trusses. At least two
bolts at base and one bolt at top should be provided
to ensure safety against collapse. The required
number of purlins should be duly fixed on the trus-
ses, generally aided by wooden cleats or iron straps.

6.3 Spreading of Roof Covering

Precautionary measures should be adopted while
fixing the Corrugated GI or AC sheets over the
sloped roof. Due overlapping at the ends and edges
of the sheets, screwing the sheets with purlins and
fastening by J-hooks, etc are the requisites for safety
against storms, cyclones, etc. While laying a"d
fixing the sheets, from eave to ridge, the carpenters
should not move over the sloped roof to avoid
slipping down inadvertently. Wooden or bamboo
poles may be stretched horizontally over the lower
end of the sloped roof to facilitate easy working and
safe movement of the carpenters as described in
5*5, Tneir tools may also be kept leaned against this
type of temporary supports which will have to be
raised or pulled towards the ridge depending on the
progress of work. Sufficient number of labourers
should be engaged to lift or carry up the necessary
materials including Corrugated GI or AC sheets,
tim.ber purlins, etc and there should be clear signals
and shoutings at the start and end of the lifting
work to avoid any untoward happenings.
Workers engaged in the work should use safety
dress materials (see 5.1) including cat ladders and
safety harness.

7 WARNING SIGNALS

7.1 Adequate warning signals, notice boards, cu:
should be depicted at or near the working places
highlighting the danger Involved innon-obscrvancc
of safety rules. In addition to written signals, there
may also be occasional verbal warnings sounded by
the supervisors, senior or experienced workers su
that the busy workers may noi he in diffieuliy even
when they inadvcrtcnily Itirget the basic saleiy
rules.

IS 13416 (Part 4 ) : 1994

7.2 In the workplace, there should be adequate
quantity of safety equipment, garments, shoes, hel-
mets, etc as per the number of workers to be
engaged. The supervisor should ensure that no
person in workplace violates the safety rules even
in short or temporary absence of the supervisor.

8 PRECAUTIONS

In addition to the specific provisions, following
precautions should also be adopted:

a) Trusses should be carefully handled while
tilting up as very large stresses and bending
moments arise in the upper chord due to its
possible bending out of the plane and rever-
sal of stresses may also take place.

b) Framing presents problem after erection
had commenced and joists, purlins, sheath-
ing, etc are still not provided. This skeleton
may need adequate bracings to protect com-
pression members in particular and the
frame as a whole until structure is complete.

c) The sling points should be suitably posi-
tioned from safety considerations par-
ticularly in case of laminated timber
constructions involving use of small dimen-
sioned limber as slings may have embeding
effect in timber pieces due to pulls and self
weight of structural component. Similarly

.. adequate precaution should be taken while
unslinging under unfavourable conditions
of height after the structure has been
hoisted in place.

d) While using scaffolds and ladders the
provisions for safety given in^ IS 3696 (Pan
1) : 1987 and IS 3696 (Part 2) : 1991 respec-
tively should be followed.

9 TRAINING

The carpenters should be imparted basic training
in respect of dangers associated with the works and
the methodology of avoiding the dangers for
smooth and speedy completion of the work.

ANNEX A

( Clause 2 )

LIST OF REFERRED INDIAN STANDARDS

IS No.
2366 : 1983

2925 : 1984

3364 (Parti)
1976

Title

Q)de of practice for nail-jointed
timber construction (first revbion)

Specification for industrial helmets
(second revision)

Methods of measurement and
evaluation of defects in timber;
Part 1 Logs (first revision)

3364(Part2): Methods of measurement and
1976 evaluation of defects in timber:

/5A^a Title

Part 2 Converted limber (first
revision)

36% (Part 1): Safety code of scaffolds and lad-
1987 ders : Part 1 Scaffolds

3696 (Part 2) : Safety code of scaffolds and lad^
1991 ders : Part 2 Ladders

11096: 1984 Code of practice for design and
construction of boit-joinied timber
construction

IS: 13416 (Part4): 1994

ANNEX B

( Foreword )

COMMITTEE COMPOSITION

Safety in Construction Sectional Committee, CED 45

Chairman
MajGenS.N. BouRi

Members
SHRi IC S. S. Ajjan

Shri a. B. Lal (Alternate)

SHRICS. OlANDPURI

Shri D. S. Khangura {Alternate)
Chief Engineer (Training)

Superintending Engineer (Training) {Alternate)
Maj Dalbir Singh

Shrj ViiocAM Kumar {Ahemate)
DEPu^n' Director (B&S)

Assistant Design Engineer (B&S) (Alternate)
SHRI P. G. Devadas
Shri P. KL Dutia

Shri A P. Bahadur (Alternate)
Fire Adviser

Deputy Fire Adviser (Ahernate)
Shr] V. K. Jain

Dr a, K. Panda (Alternate)
DrJ. L. Jethwa

Shri M. K. Verman (Alternate)
Shr] V. L. Kathana

Shri U. B. Parelkar (Alternate)
Shrj B. B. Kumar
Shri J. L. Majiajan

Shri V. K Kasliwal (.Alternate)
Shri N. L. Mancmanda

Shri R- P. Chaturvedi (Alternate)
Shri J. P. Mital
Shri A, C. Nirwani

Shrj a K. KhanNA (Alternate)
Shrj Umakant B. Parelkar

Shri A L. ChhaIT^E (Alternate)
Shri A J. Patankar

Shrj D. M. Srivastava (Alternate)
Shri Agia Ram

Shri G. K Tika {Alternate)
Shri S. A Reddi

SHW V. M, Dharap (Alternate)
Shrj A J, Rego

SHRJ R, p. Bhanushali (Alternate)
Shri S. Roy

Shrj M. Kundu (Alternate)

Shri D. S. Mishra (Alternate)
Dr Govind Sachdev
vShri S. N. Sanyal

Shri H. N. Misra (Alternate)
Shri Jay Prakesh Sathe

Shrj ABHaY KhuRJEKAR (Alternate)

Shrj Sadanand Satpijte (Alternate)
Shri S. K Guka Thakurta
ShriS. K GuhjvJ^iakurta
ColT. P.Tyagi

Shri N. K Bhattacharya (Alternate)
Shri 3. Venkataraman,

Director (Civ Engg)

Representing
Engineer-in-Chiefs Branch, Army Headquarters, New Delhi

National Thermal Power Corporation, New Delhi

Central Water Commission, New Delhi

Central Public Works Department, New Delhi

Builders' Association of India, Bombay

Ministry of Railways (RDSO), Lucknow

Acrow India Ltd, Bombay

Ministry of Surface Transport (Roads Wing), New Delhi

Ministry' of I lome Affairs (Fire Services), New Delhi

Steel Authority of India Ltd, New Delhi

Central Mining Research Station, Dhanbad

Ministry of Labour (DGFASLl), Bombay

National Buildings Consiruclion Corporation Lid, New Delhi
Geological Survey of India, Calcutta

Rashtriya Pariyojna Niniiar Nigam Ltd, New Delhi

The Institution of Engineers (India), Calcutta
Hindustan Construction Co Ltd, Bombay

The Indian Institute of Architects, Bombay

Hindustan Steelworks Construction Ltd, Calcutta

Central Road Research Institute (CSIR), New Delhi

Gammon India Ltd, Bombay

National Safety Council, Bombay

Hindustan Prefab Ltd, New Delhi

In personal capacity (J 1374, Palam Vihar, Dist Gurgaon, Han,'afui 1 '^2017)
Forest Research Institute, Dchra Dun

Fabricare, Punc

National Institute of Construction Management aiul Research, Bombay
Gannon Dunkerley & Co Ltd, Bombay
F.ngineer-in-Chicrs Branch, Army \ leadquariers. New DcUii

Director General, BIS [lix offtcio Mcrnhcr)

Member Secretary

Shri Sanjay Panj
Assistant Director (Civ Lngg), BIS

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